Kernel Recovery Mode - ZyXEL Communications U-336E User Manual

Kernel Recovery Mode

Your modem is equipped with ZyXEL's exclusive Kernel
Recovery Mode. This unique feature enables quick recovery from
failed flash uploads. With other modems, a failed flash upload
usually results in the user having to return the modem to the factory
for repair.
In the unlikely event that your modem fails to respond to AT
commands after upgrading the flash EPROM:
1. Turn off the modem.
2. Press the D/V button while turning on the modem, then release
the button after 5 seconds.
A Kernel Program responsible for the update process takes
control of the modem. It accepts a limited set of AT commands,
including the ATUPX command.
3. Repeat steps 1 through 9 from the previous directions above to
upload a file that contains the valid firmware for your modem.
Upgrading Your Modem 119